Horizons Regional Council Biosecurity Officer, Robert Bashford, and his contractors have been using various methods including knapsack-spraying to control Darwin’s barberry (Berberis darwinii) in the wetlands of National Park village. It is hard work and they can’t find all the barberry they know is in there. The safety issues in the wetland are too high to continue with ground methods. Robert tried a helicopter, but this was overkill for the size of the infestations and the precise spraying required, and it was a bit close to the village. Robert says,

“the detection and control of Darwin’s barberry in these wetlands is a perfect situation for the aerial drone methods Flightworks has developed.”

Flightworks collected high-resolution images by aerial drone across the wetland and searched these for Darwin’s barberry in flower using an automated supervised classification and a visual search.

Darwin’s barberry detected amongst other similar looking weed species (gorse/broom)

Then an aerial spray drone was flown to the barberry waypoints. Barberry was identified using onboard cameras and then sprayed precisely via a controllable spray wand. The flight log and control data were captured so that these sites can be inspected again for the next generation of seedlings. The operation was undertaken as a Permitted Activity under the Horizons One Plan (with relevant consultation) as it is a low volume application more closely related to knapsack spraying than helicopter spraying.

“Flightworks use drone technology to make a significant difference in weed detection and control projects where other tools cannot. They take a professional approach to the project utilising their ecological, mapping and flying expertise.”

Aerial drones are being used for an increasing variety of projects by councils. For biodiversity, biosecurity and compliance monitoring; for infrastructure planning and inspection, and for emergency response situations.

Today we look at three Flightworks aerial surveys undertaken for the Bay of Plenty Regional Council, highlighting just some of the useful applications for drones.

Spartina monitoring – Maketu estuary

Spartina is a weedy grass being targeted for eradication in the Maketu Estuary. Having a good monitoring system to track progress towards this goal is key to success. Flightworks was engaged to provide a high-resolution orthomosaic image of the spartina infested areas in order to provide a baseline for this project.

For any project like this, it’s important to decide which image resolution will achieve your objective. Higher resolution requires lower altitude flying and longer flight times, increasing the complexity and cost of the orthomosaic.

For example, at Maketu we chose 1.95cm pixel resolution to broadly record the change in vegetation as per the project goals. Whereas, if we had needed to detect very small areas of spartina we would have chosen a higher resolution.

The series of images below give an indication of pixel resolution – in the photo from top to bottom is: spartina, a stick, mud with crab holes, and a sea rush.

2.60 cm pixel resolution

1.95 cm pixel resolution

1.30 cm pixel resolution

0.65 cm pixel resolution

“Hamish and his team at Flightworks have been great to work with and have provided a professional and high quality service. They invested time in planning the project with us to ensure they could provide us with the best product for our needs. The orthomosaic imagery has provided us with a valuable tool for monitoring and was able to be carried out much faster and more safely than could be done on land, or in the estuary!”

Dune vegetation – Ohope spit dune

Rabbits are devastating the native vegetation across the Ohope spit dune so the BOP Regional Council is preparing a comprehensive pest control plan. To provide a baseline for the expected changes in vegetation as a result of this initiative and to plan for weed control, Flightworks were engaged to provide a high-resolution orthomosaic of the dune spit.

While flying, we also captured 10 aerial oblique photos from planned vantage points in the sky, which give a larger landscape perspective across all parts of the dune. These were documented as aerial photo-points so that they can be repeated. For photo-points, the client wears goggles with a direct view through the drone camera to assist framing the camera shots.

“After recently engaging Flightworks to undertake aerial mapping and photography for a Biodiversity Project I manage on the Ōhope Sand Spit, I would highly recommend them, especially when it involves operating in a public area. Flightworks had exceptional health and safety systems and were very professional in every aspect of their operation. The outputs were great and all the partners and I of the project were blown away with the results. This work has proven invaluable in helping plan detailed pest plant work, and will provide a great baseline for assessing on-the-ground changes over time.”

Infrastructure planning – Tikitere stream

The BOP Regional Council is considering a water denitrification plant beside the Tikitere Stream. The plant would remove ammonia from the water in the geothermal stream to decrease nitrogen pollution of Lake Rotorua.

The site beside SH30 has recently been cleared of vegetation, which provided an excellent opportunity to create an accurate point cloud of the ground levels for engineers and planners to model the plant building positions.

Flightworks flew the site to create the point cloud and orthomosaic for the planning work. A set of six Ground Control Points (GCPs) were marked across the site and surveyed to 2cm accuracy. These could be clearly seen in the aerial imagery and the 2cm accuracy was conveyed through the processing into the final orthomosaic and 3D model.

Yellow GCPs across the 3D model

“Flightworks provided superb high quality aerial imagery and point cloud data for the BOP Regional Councils Tikitere property and the data from this was used to design a nitrogen reduction plant. Flightworks were professional and thorough at all stages of the project from scoping project works right through to advising end-users on how best to use the data.”

— Robbin Britton, Consultant Project Manager for BOPRC

Talk to us

At Flightworks, we use aerial drones as a revolutionary tool to complement our expertise as ecologists.

Call me (Hamish) on 07 394 4394 if you have any questions about this article, or contact us if you’d like to discuss your project requirements.

Aerial drones capture amazing images. The aerial perspective and the image resolution provide a level of detail that is hard to beat. Much more than just pretty pictures, aerial images are a powerful tool for land management projects.

But using aerial drones to capture the image is just the start. Making good use of the image is where the rubber hits the road.

Here are three ways to use aerial images to really step-up your projects.

1. Smartphone orthomosaics

Take the high-resolution orthomosaic images captured by a drone with you into the field on your smartphone. Of course, the ability to take orthomosaics into the field has been with us for years, but now smartphones take it to a new level. With their computer power and smart apps, smartphones provide a very useful GIS tool. You can track where you are, mark waypoints, add notes from drop-down menus, attach photos, or draw polygons right onto your orthomosaic.

The orthomosaic becomes an interactive working tool. The accuracy is amazing.

Screenshot of a smartphone using an orthomosaic in the field to record data about the site.

Utilising the high resolution of an orthomosaic for detailed aerial views in the field.

2. Colour analysis weed search

High-resolution orthomosaic images have a lot of pixels. In a single 10mb photo taken with a 24MP camera there are 24 million pixels. An orthomosaic can be made up of thousands of photos – that’s a lot of pixels!

You can take advantage of all these pixels by employing an automatic search of pixel colour in the orthomosaic to look for weeds. We use this technique to focus our attention on areas more likely to have the weed. We sample the colours of the target weed, then search for pixels of those colours in the rest of the orthomosaic.

This method might not find the last weed present in your area, but it is a powerful visual aid to quickly focus your attention to weeds that your eye may not see in a visual grid search. It can significantly speed up the process of detecting and targeting weeds.

An orthomosaic of a raupo-dominant wetland. The weed royal fern is difficult to visually detect amongst the other brown colours (scale 1:1,000)

Sites suspected to be royal fern detected by a colour analysis of pixels (scale 1:500)

Close-up of a known royal fern, showing the distinctive reddy-brown colours. These pixels are sampled to use as a reference to search for other pixels of the same colour (pixel size=2cm).

3. Aerial photo-points

As ecologists, we often use photo-points on the ground to monitor changes in an area over time. Photo-points can also be done in the sky using GPS to record the exact position, altitude, and bearing of the drone for repeat images overviewing an area.

These aerial waypoints are delivered to the client so you can understand where each photo has been taken from. The photos can even be associated with the waypoints in your database so they can be viewed when clicking on the waypoint. When it is time to monitor the site again, we load the waypoints into the drone and send it back to the same spot in the sky!

Wetlands are valuable ecosystems found across our landscapes from estuarine to alpine areas. They are receiving increasing attention as we manage our freshwater and coastal resources more intensively.

The trouble is, wetlands can be difficult to monitor due to accessibility. But now using aerial drones, we can monitor biodiversity values and biosecurity issues from an aerial perspective.

Aerial drones are now accepted as part of the toolbox for monitoring all sorts of projects efficiently and effectively. Drones are most commonly used to create aerial photography and orthomosaic images, but have an increasing list of abilities to provide data and services from the air. They provide a method to accurately monitor changes in natural features over time, and a cost-effective tool to understand the requirements and priorities for management.

Three aerial surveys that Flightworks has recently undertaken show some of these applications for aerial drone monitoring of wetlands.

Vegetation type mapping – Otakairangi wetland

The Department of Conservation manage the 265ha Otakairangi Wildlife Management Reserve north-west of Whangarei. It is a remnant peat bog wetland with a mosaic of native and weedy vegetation types. To help with restoration management of the wetland Flightworks was contracted to provide a high-resolution aerial image, and then define the broad vegetation types and weed locations across the wetland. The image below shows the GIS map layers of the project: orthomosaic (with reserve boundary), vegetation types and weed locations.

“The Flightworks team provided a great service for the project in Otakairangi including a comprehensive vegetation type analysis and interactive point cloud of the wetland reserve. Flightworks were extremely professional in executing the required work through their extensive ecological knowledge and aerial photograph/mapping skills backed up by a strong emphasis on Health & Safety. The team were flexible and happy to devote time to understand the scope of the project thus producing a comprehensive report and associated aerial photography meeting the contract requirements”

Aerial monitoring – Whangamarino wetland

As part of the resource consent for a river weir at Whangamarino wetland, the Department of Conservation is required to take aerial photographs at fixed points, which are then analysed to identify changes over time in vegetation composition and channel encroachment. Flightworks provided the aerial photography and mapping services at several sites throughout the wetland. The orthomosaic of the Whangamarino River area below is zoomable, and shows the clarity of image resolution at 3.4cm/pixel compared to the background Google Earth imagery. Images like this can be created with finer resolution according to needs.

“The team at Flightworks were wonderful, working closely with us to fully understand the scope of the work and to overcome any logistical challenges the work or the wetland created. I was especially impressed with the level of communication throughout the project, which made working with the Flightworks team very easy. They provided a highly professional service, fully meeting the requirements of the aerial photography contract including providing an excellent field report at the end of the project.”

Restoration planning – Kaituna wetland

The Bay of Plenty Regional Council are planning the re-creation of freshwater wetland to extend the Kaituna wetland. Flightworks was hired to provide a high resolution orthomosaic to help with the planning for the restoration, and to create a benchmark to monitor progress of the project. Oblique aerial photos provided a variety of aerial perspectives, and a 3d point cloud model of the wetland enabled a virtual fly-through to help provide an overview of the project area. View a video of a fly-through of the wetland below.

“BOPRC engaged Flightworks to take high-resolution aerial photographs of 280 ha of the Lower Kaituna Wildlife Management Reserve and adjacent areas and to create an orthomosaic and point cloud. Despite problems with the weather Flightworks completed the work to a good standard and the final product is very useful as a management and planning tool for wetland development and restoration.”

Have you thought about adding aerial drones to your weed control arsenal?

Using aerial drones for weed control is a relatively new application. So where do drones fit into your spraying toolkit? And what advantages do they offer?

Harness the capabilities of drone spraying to help your weed control programme

Here are 4 drone-perfect scenarios:

When spray sites are difficult to access: Control weeds safely

When you need precise spot spraying: Targeted control

When you need an accurate spray record: GPS tracking

When you need to minimise disturbance: Discrete and quiet

Let’s take a look at these in more detail…

1. When access to weeds is difficult or hazardous

Is your spray area difficult or dangerous to access?

Examples of valuable ecological areas that can be difficult and dangerous to access on foot for weed control include:

Wetlands. Foot access can be impossible through dense vegetation

Geothermal. Ground access is dangerous due to thermal activity

Sand dunes. It can be difficult to traverse back-dune vegetation

Areas such as these provide challenges for weed control with extra time, expense or risk (and possibly all three).

Provided that the operation is within the capability of a drone (line-of-site visibility and size of weed control area), aerial drone spot-spraying can be an effective and safer alternative to ground-based or helicopter operations.

2. When you need precise spot spraying

Some spray areas are sensitive, for example, sites with valuable plants or around waterways. You can’t afford mistakes. Using an aerial drone enables you to detect, map and control weeds with precision.

The blanket spraying of weeds can often encourage their re-establishment. Spot spraying, on the other hand, can pick out the weeds from desirable plants for enduring weed control.

The flight team can fly the drone over the target weeds and spray them with the same accuracy as by hand. No overspray, no rotor wash, no danger to staff.

3. When you need an accurate spray record

Killing a weed often provides a space for its seeds to germinate underneath. So, it is necessary to return to that precise location to check and control the next generation of weeds until its seed bank is exhausted.

An aerial drone has the ability to track everywhere the drone flies and where it sprays. This information is recorded in a GPS track file which can be kept as a record, and used to return to all weed control sites the following season. The spray track records also provide evidence of the flight and spray paths in case there are concerns from the public.

4. When you need to minimise disturbance

Using an aerial drone is a good alternative to using a helicopter when there are potential issues with public perception, noise, or spray drift.

It could be you need to spray in an urban area, near waterways or other sensitive areas like orchards. With a drone there is less disturbance to neighbours and the public.

A spray drone can operate and spray relatively un-noticed and with precision. We’re not talking covert. We mean within aviation law and regional plans for aerial spraying, including notification. A drone is smaller, quieter and more accurate than a helicopter. This can be useful to manage public perceptions and minimise complaints while getting the job done.

Wait! Map your weeds first!

In a previous blog we talked about how to use an aerial drone to map and locate weeds to plan your spray program. For aerial drone spraying, having a map with GPS waypoints of weed sites that have already been detected is the best way to find and target them. The drone can then fly directly to the target weeds for control.

To ensure a well-timed and targeted weed control programme it is important to know the weeds that are present and their location. Ask yourself these questions:

When is the best time to detect species from the air – With leaf? When flowering? When other vegetation has died back for winter?

When is the best season to spray?

When do the weeds produce seed?

Talk to us

At Flightworks, we use aerial drones as a revolutionary tool to complement our expertise as ecologists.

Call me (Hamish) on 07 394 4394 if you have any questions about this article, or contact us if you’d like to discuss your project requirements.

There are a number of weed control methods out there. The trick is to choose the most effective method for your project – and it could be that you need a combination of methods to achieve comprehensive weed control.

So let’s take a look at the options and the advantages of each weed control method.

Ground-based weed control

Ground weed control has a major cost advantage if the weeds can be safely and efficiently accessed. Methods include drilling, cut/paste, knapsack, or a hose or boom on a vehicle or boat.

There are advantages in being able to directly identify and target weeds from non-target plants, and find weeds hiding in places that may be unseen from the air.

However not all sites have easy access via the ground which is the limitation of this method.

Abseil weed control

Abseiling is suitable for accessing steep areas where there is good rope fixing points above.

The key advantage to abseiling is being able to closely investigate areas inaccessible from the air. Abseiling is ideal for detecting and accessing weeds that may be hiding behind other plants and therefore not detectable from above. If weed control in steep areas requires cutting/pasting then this method is a great solution.

Helicopter weed control

Helicopters are the best tool for spraying large areas of weeds efficiently, especially in areas inaccessible for efficient ground control. The ability to access remote areas across a large landscape is the most significant advantage of using a helicopter.

Using a helicopter for aerial application is much faster than ground work or aerial drones over a large area. Thus larger areas can be covered with greater economy.

Aerial drone weed control

Operator safety is a major advantage of using aerial drones over helicopter or abseil methods where people are in the air. Aerial drones are also advantageous where access is difficult or dangerous on foot (e.g. cliffs, geothermal, wetlands, or when wasps are present).

Aerial drones can also access some places that other methods (including helicopters) cannot access at all. Drones can therefore help detect and control the last weed populations where eradication is the goal.

Aerial spray drones can also record GPS waypoints to pinpoint weeds that have been sprayed. This allows for accurate and efficient re-visiting of sites for weed control and monitoring. The spray techniques precisely spray the target while avoiding damage to sensitive areas.

Drones are much quieter and less intrusive than helicopters when noise and disturbance is an issue.

With a relatively limited payload capacity, spray drones are suited to smaller scale operations, and are often restricted to flying within line-of-sight of the operator. However, drones can efficiently access weeds that are scattered across a difficult site.

How will you target weeds?

As you can see, there are many options.

In many cases, you may want to undertake the easily accessible or broadacre weed control method first, and then see what remains and utilise an aerial drone for eradication.

Call me (Hamish) on 07 394 4394 if you have any questions about this article, or contact us if you’d like to discuss your project requirements.

Aerial drones are now being used for all sorts of commercial applications. They are an extremely nimble aircraft which means they can provide safe access to difficult sites. Add to this the ability to carry a variety of payloads, and you have a very useful tool at your disposal.

But not all drones or drone operators are equal. So how can you be sure you’re choosing the right drone operator for your project?

You’ll need to make sure any contractor you hire has the necessary skills and operational procedures in place to ensure your project goes smoothly.

For agencies looking to hire a drone operator as an Approved Contractor, here are 7 things to consider…

7 things to consider before hiring a drone operator

1. What are the capabilities and limitations of the drone services?

It’s important to understand the capabilities and limitations of the drone services that can be provided. Basically, does the contractor have the skills and equipment needed to complete your project?

Do they have expertise relating to the project?

Can they carry the required payload or equipment?

Are the camera specifications adequate?

Can they cover the distance required?

Is the imagery geo-referenced to the required accuracy?

What weather conditions limit the operations?

What capacity does the business have for the volume of work that needs doing?

2. Is the drone pilot certified?

Currently drone pilot certification is required only in certain aviation control zones. However, for commercial operations, you may expect drone pilots to be certified as confirmation of their ability to fly drones anywhere.

Certificates under Part 102 of the Civil Aviation Authority Rules are required for any drone flying that is outside of the normal flying limits for drones under rule Part 101. A Part 102 certificate is necessary for any flying above 400ft, at night, beyond line-of-sight, over people and property without their permission, or for releasing hazardous substances. The certificate also ensures that safety systems are in place for all flying scenarios.

For commercial applications, drones must be treated as aircraft – not toys.

Request confirmation that there are policies and procedures in place to ensure safe drone-flying operations. Operators should follow aviation rules and have procedures for flight plans and flight logs, as well as understanding how to manage any potential privacy issues.

5. Is there an aircraft maintenance plan in place?

As with all aircraft, preventative maintenance is imperative to ensure safe flying at all times. Aerial drone maintenance programmes are part of good aviation practice, and evidence of this should be expected from any commercial operator.

6. Have they signed the UAVNZ Code of Conduct?

The Unmanned Aerial Vehicles New Zealand (UAVNZ) is the Industry Group for commercial drone operators. They recently introduced a Code of Conduct for members in order to ensure safety and professionalism in the industry. This is a membership that should be expected of a professional drone operator.

7. Does the operation have a comprehensive Health and Safety Plan?

A Health & Safety plan is compulsory for any Approved Contractor. Be aware of the new requirements of Worksafe coming out in April 2016. Also, the jurisdiction of safety is split between Worksafe when drones are on the ground and Civil Aviation Authority once they are airborne.

And lastly, are they proficient? You may want an aerial drone demonstration to get a feel for how an organisation operates in the field before hiring them.

Talk to us

At Flightworks, we use aerial drones as a revolutionary tool to complement our expertise as ecologists.

But before we cover how aerial drone mapping for weed control works, let’s look at why aerial drone mapping is such a helpful tool in the first place…

The advantages of aerial drone mapping

Aerial drones have provided a revolution in photogrammetric mapping, because they provide high resolution orthomosaic images on-demand which are repeatable over time. Introducing these georeferenced images into mapping software allows for accurate measurements, and this is useful for survey and monitoring projects. For weed surveys the aerial perspective allows you to detect weeds that cannot be seen from ground level.

How aerial drone mapping for weed control works:

Firstly, it is important to choose the season where your target weeds can be seen most clearly amongst their surrounding vegetation in an aerial image. In special mapping software you can plan weed control by measuring areas of weeds and marking infestations with waypoints. When it’s time for weed control these areas and points can be uploaded onto gps to allow direct navigation to the weeds (by foot, vehicle, boat or aerial). Sometime later, another aerial map can be created to check on the control work and see if any weeds have been missed or appeared since the control work.

High resolution aerial imagery can also help detect the very last weed plant in an eradication programme before it seeds back into your area. The spectral analysis of aerial imagery can help detect these last weeds where the human eye may not see them. A spectral analysis of images measures the amount of reflected light from a surface. Images are taken and numerical values assigned to each pixel, utilizing a range of wavelengths across the visible and infrared spectrum. Through the use of specialized software and statistical analysis, these pixels are characterised to distinguish between plants.

It is well understood how enormous the savings on weed control costs are when a weed can be eradicated. Having comprehensive, high resolution aerial imagery may help achieve this.

5 steps for aerial drone weed control:

Fly over the area of interest and create an orthomosaic image

Detect weeds visually and with spectral analysis

Mark the location of weeds with waypoints

Send out your weed control team to the waypoints to control the weeds.

Repeat steps 1 and 2 to monitor weeds, and then 3 and 4 as necessary!

Call me (Hamish) on 07 394 4394 if you have any questions about this article, or if you’d like to discuss your project requirements.